The present invention relates generally to a vehicular lamp, and more particularly to a vehicular lamp having an improved light emission efficiency, while having a reduced size and slim body.
FIG. 4 is a sectional view showing a conventional vehicular lamp. The lamp is provided with a resin-molded lamp body 101 constituted by peripheral walls 111 in a rectangular frame shape and a parabolic-shaped rear wall 112 molded unitarily with the peripheral walls 111 at the rear side thereof. Inner surfaces of the lamp body 101 are coated with aluminum or the like to provide a reflective surface, and an opening is formed in the rear wall 112 to constitute a bulb mounting hole 113 into which a bulb socket 103 is fitted to mount a bulb 104 inside the lamp body 101. A transparent front lens 102 is integrally secured over a front opening of the lamp body 101.
The vehicular lamp is also provided with a vent 114 in the rear wall 112 so that the interior of the lamp body 101 is ventilated, thereby to avoid undesirable condensation and accumulation of moisture on the inner side surfaces of the lamp body 101. Generally, the vent 114 is defined by a cylindrical member extending to the outside from the lamp body, and capped with a cover tube 115.
In a conventional lamp body formed by resin molding, the bulb mounting hole 113 and vent 114 extend in the direction in which the molded product is extracted from the mold die in order to simplify the structure of the mold dies and to allow for the easy removal of the lamp body from the mold. Because the removal direction of the lamp body 101 (indicated by arrows Y in FIG. 4) is in the front-rear direction of the lamp, the bulb mounting hole 113 and the vent 114 are formed on the rear wall 112 of the body 101.
If the vehicular lamp is generally rectangular in shape, the inner surface of the parabolic-shaped rear wall 112 must provide the entire effective reflecting surface 116 used to obtain the desired light distribution pattern. Accordingly, the conventional lamp, where the bulb mounting hole 113 and vent 114 occupy a part of the rear wall 112 as shown in FIG. 4, suffers from a problem in that the area of the effective reflecting surface 116 is reduced, and the reflection efficiency of light emitted from the bulb 104 reduced, as a result of which the light distribution characteristics of the lamp are deteriorated.
Moreover, when such a lamp is viewed from the front of the vehicle, the bulb socket 103 fitted in the bulb mounting hole 113 and vent 114, both disposed on the effective reflecting surface 116, can be observed through the front lens 102 as black shadows. This deteriorates the outward appearance of the lamp.
Further, since the bulb socket 103 and the cylindrical member and cover tube 115 of the vent 114 protrude rearward from the rear wall 112 of the lamp body 101, a compact and slim lamp cannot be obtained.